This invention relates to an ignitor for movable wick type of oil stoves, and more particularly an improved ignitor utilizing discharge phenomenon for effecting the firing of the wick.
The conventional ignitors for use in oil stoves are such that they may fire the wick from inside an inner flame cylinder by forcing a heater into direct contact with the wick to fire the wick from outside the periphery of the wick by means of the heater. Alternatively, the wick may be fired through an openable ignitor window outside the wick by forcing a heater into direct contact the wick upon actuation of a push button or a knob. Still another way to fire the wick is by use of a pilot wick.
An example of the conventional ignitor assembly is now described in more detail by reference to FIG. 1. A stove base board 1 is seated on the periphery of a wick cylinder 2 and a rotary sheet 3 is held rotable by means of a shaft 4 and an elongated hole 5. The shaft 4 is mounted on the base board side 1 and the elongated hole 5 is mounted on the rotary plate side 3 in the shown example so that the rotary plate 3 is slidable about the pivot A, though it is not limited thereto as to location. An ignitor handle 6 is disposed outside the rotary plate 3 and held so that its end contacts an edge portion of a cylindrical casing 9 constituting a combustion chamber together with an inner shell 7 and an outer shell 8 so as to hoist the combustion chamber during rotation. The remaining end of the rotary plate 3 is provided with a bent portion 11 which abuts on a heater angle 10 held rotable by means of a shaft 24 as a fixed pivot B and rotates the heater angle 10 during rotation. A heater mount 13 is secured on the heater angle 10 for installation of an ignitor heater 12 by cauking or otherwise as well as a movable contact 15 which mates with a stationary contact 14 seated on the base board side 1 to set up an ignitor heater switch. To return the heater angle 10 to its home position upon completion of ignition, a spring 16 is mounted on a shaft 24 with its end secured on the heater angle 10 and the other end secured on part of the base board 1.
There is further provided a wick 17, an inner shell 18, an outer shell 19, lead wires 20 and 21, fixtures 22 and a wick adjust knob 23. The ignitor heater 12 is constructed as shown in FIG. 2, wherein a plug 24 includes a pair of standing electrode rods 26 each having an outwardly oriented tip portion serving as a contact 25 and a heater coil 27 extending between the electrode rods 25 (with a slight space with respect to the wick when the contacts 25 are in contact with the wick of an oil stove). The heater coil 27 is held in parallel with the contacts 25.
The plug 24 has a cover 28 concealing the electrode rods 26 and the heater coil 27 with its tip portion substantially level with the contacts 25. The electrode rods 26 are seated in an insulator 29.
When the ignitor handle 6 on the rotary plate 3 is turned down in the direction of the arrow C, the rotary plate 3 rotates about the pivot A and hoists at its one end the combustion chamber in the direction of the arrow D. At the same time the bent portion 11 slides frictionally on the back of the heater angle 10 rotable about the pivot B and then rotates the heater angle 10 in the direction of the arrow E so that the heater coil 27 comes into contact with the heater coil 27 of the ignitor heater 12. In the course of this movement the movable contact 15 resting on the heater angle 10 is brought into contact with the stationary contact 14 on the base board 1 so that the ignitor heater 12 is energized to fire the wick 17. Upon completion of ignition the heater angle 10 returns to its home position by the action of the spring 16 and the rotary plate 3 also returns to its home position.
Since in the above example the burner assembly is hoised and the heater angle 10 is rotated so as to force the ignitor heater 12 into contact with the wick 17 through mechanical interconnection upon the turning movement of the handle 6, smooth and stable ignition demands strict specifications of these components. For example, an error on the order of millimeters is not permissible in connection with the spacing between the the heater coil 27 and the wick 17. Very skillful machining is necessary for preparation of the components during manufacture of the ignitor assembly. If such machining is not successfully accomplished, faulty components sometimes result. In other words, installation of such an automatic ignitor assembly on oil stoves provides a convenience for the operator but results in complexity of the structure and manufacture of oil stoves. This also requires precise machining tools and machines and inevitably increases the cost.